When researchers at the University of Pittsburgh pooled the data from nine large studies that involved more than 34,000 seniors, they were able to correlate walking speed in people 65 or older with expected longevity.

At the beginning of each study, subjects were timed at their normal, comfortable walking pace for about 13 feet and periodically retested for up to 21 years. Anyone who could ambulate, even if they used a cane or walker, was included.

The faster an older person can walk, the longer they can expect to live and, according to the researchers, walking with some pep in your step appears to be a better predictor of who survives than simply looking at someone's age and sex.

"It's a real part of the human experience to see that when someone slows down with age, they may not be doing as well as they once were," said lead researcher Dr. Stephanie Studenski. "One of the major goals of this study was to quantify this experience for practical and clinical purposes."

Studenski notes that the act of placing one foot in front of the other requires the cooperation of many body systems including the heart, lungs, blood, bones, muscles, joints, nerves and brain -- and all of these systems synchronize, coordinate and integrate in a way that allows each individual to choose their own ideal walking speed, a speed that remains remarkably constant throughout life unless it's affected by medical issues.

For this reason, scientists consider how quickly a person walks, when correlated with age and sex, a reflection of their underlying health.

Someone like Gerjouy, for example, who at his age still strolls comfortably at about 3 miles per hour, can expect to enjoy another seven years of life. In contrast, a 75-year-old man who barely shuffles along at less than 1.0 mile per hour may not make it to his 80th birthday; and a 75-year-old woman who can keep pace with Gerjouy may look forward to celebrating another 18 birthdays.

"In fact, speed of movement seems to be linear, with each increase correlating with an increased prediction for years of life," Studenski said.

Walking Speed Tests Could Guide Doctor Advice

Administering a simple timed walking test could prove useful for helping doctors make more individualized healthcare recommendations. For instance, prostate cancer screening is generally considered a waste of time for men over 70 because it is widely accepted that elderly men who develop prostate cancer will most likely die of another disease or natural causes.

But if an energetic walker in his seventies can reasonably presume to live another decade in good health, he could benefit from the screening.
"Functional predictions like this give doctors an opportunity to do individual life planning for healthy older people where we ought to treat them like they are going to be around for a good long time," Studenski said.